The present invention relates to devices and methods for sensing condensation conditions and for removing such condensation from surfaces such as vehicle windscreens, helmet visors, computer monitor screen, windows, electronic equipment, etc., and especially devices and methods that use a thermoelectric cooler (TEC) for automatically and dynamically sensing condensation conditions when condensation appears on a surface or before such condensation actually appears on a surface.
The level of moisture in air at any time is commonly referred to as relative humidity. Percent relative humidity is the ratio of the actual partial pressure of steam in the air to the saturation pressure of steam at the same temperature. If the actual partial pressure of steam in the air equals the saturation pressure at any given temperature, the relative humidity is 100 percent. If the actual partial pressure is half that of the saturation pressure, the relative humidity is 50 percent, and so forth.
Dew point temperature, also known as condensation temperature or saturation temperature, is a function of the level of moisture or steam that is present in the air, and is the temperature at which air has a relative humidity of 100 percent. Condensation of moisture on a surface occurs when the temperature of that surface is at or below the dew point temperature of air surrounding the surface.
When air having a relatively high content of moisture comes into contact with a surface having a temperature at or below the dew point temperature, steam will begin to condense out of the air and deposit as water droplets onto the surface. At this time, a thin layer of liquid water comprised of small water droplets forms on the surface, creating a visual hindrance or xe2x80x9cfogxe2x80x9d to an observer looking at or through the surface. Once, formed, the condensation can be dispersed and removed either by raising the temperature of the surface, thereby changing the water into steam, or by lowering the relative humidity of the air surrounding the surface, thereby allowing the droplets to evaporate.
The invention provides a device and method for sensing condensation and for removing such condensation from a surface. A first thermal sensor is in thermally conductive contact with the surface. A second thermal sensor is in thermally conductive contact with a cooling device. A circuit activates the cooling device in order to maintain the second thermal sensor at a temperature that is lower than a temperature of the first thermal sensor. A humidity sensor is in thermally conductive contact with the cooling device. A circuit causes a condensation removal mechanism to be activated for removing liquid from the surface when the humidity sensor indicates a presence of condensation at the temperature that is lower than the temperature of the first thermal sensor.
The invention provides a convenient and practical mechanism for detecting condensation conditions quickly, and possibly before they manifest themselves on the surface. In certain embodiments the condensation removal mechanism can be activated automatically when a condensation condition is detected, thereby providing convenience and safety where the surface is a windscreen of a vehicle, for example, or a helmet visor, computer monitor screen, window, electronic equipment enclosure.
Numerous additional features, objects, and advantages of the invention will become apparent from the following detailed description, drawings, and claims.